Pressure actuated sensors form an integral part of many domestic alarm systems as well as in such used in security installations. Such a sensor is placed on a floor, on the ground or slightly below the ground's surface and when a person steps on that sensor, an alarm is initiated.
Optical fibers-based sensors play an increasingly important role in security and alarm systems owing to their reliability, durability, and the relative simplicity of the associated components. Optical fibers have accordingly found applications also in pressure sensors. In one such optical fiber-based pressure sensor, Hergalite.TM. (Herga Electric, U.K.) use is made of optical cables attached to an upper surface of a rigid support plate, the cable consisting of an external layer made of a pliable material and an internal core consisting of an optical fiber surrounded by a spiral rigid wire.
In other kinds of optical fibers-based pressure sensors, use is made of special pressure sensitive optical fibers.
In sensors of the above type, the application of pressure on the sensor causes attenuation of the light transmitted through the optical fiber.
All optical fibers-based pressure sensors suitable for use in alarm systems available to date, use very expensive hardware and such sensors are accordingly unsuitable for widespread use and their use has indeed been limited.
It is the object of the present invention to provide a pressure actuated optical fiber-based sensor which is made of very cheap and readily available hardware and is thus suitable for widespread application.